Collapsible butt-stock mechanism for shoulder-fired firearms

ABSTRACT

A firearm has a receiver extension defining a plurality of spaced butt-stock positioning receptacles. A butt-stock has a locking pin that is moveable into one of the receptacles for locking the butt-stock at a desired position on the receiver extension. A lock pin actuator is manually moveable by applying a force to a pull ring member to cause retraction of the locking pin from a butt-stock positioning receptacle in preparation for position adjustment or removal of the butt-stock relative to the receiver extension. A rotary knob lock positioning member is rotatable to locked and unlocked positions and when locked ensures against complete separation of the butt-stock from the receiver extension member upon maximum length adjustment of the butt-stock.

RELATED PATENT APPLICATION

Applicant hereby claims the benefit of U.S. Provisional Patent Application No. 61/627,993 filed on Oct. 21, 2011 by Mark C. LaRue, and entitled “Collapsible Butt-stock Mechanism For Shoulder Fired Firearms”, which Provisional Patent Application is incorporated by reference herein for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to shoulder fired firearms and more particularly concerns adjustable butt-stock mechanisms that enable firearm users to establish precision adjustment of the length of a butt-stock as desired for a comfortable fit of a firearm stock with the anatomy of the user. More particularly, the present invention concerns a firearm butt-stock that can be lengthened for use or shortened for storage or transport and can be adjusted from the standpoint of length in the event close quarter combat conditions warrant the use of a rather short and compact shoulder fired weapon. This invention also concerns firearms having butt-stocks that can be completely removed from the firearms or interchangeable with other types of butt-stocks.

2. Description of the Prior Art

Especially in the field of tactical firearms there has been a continuing need over the years for shoulder fired firearms that have butt-stocks that can be adjusted in some fashion for the purpose of changing the configuration of the firearm, primarily to establish a desired fit with the physical characteristics of the physique of the user, but also to accommodate the conditions within which a firearm is being used. Firearms have been developed that have butt-stock mechanisms that can be shortened or lengthened, even during field conditions and which can be shortened or folded so as to adapt the firearms for storage and transportation. Various types of tactical firearms have been developed that incorporate a rearwardly projecting receiver extension member, with a butt-stock mechanism that has selective position adjustment along the length of the receiver extension member so that the stock portion of the firearm can be easily and simply adjusted to fit the body anatomy of the user.

SUMMARY OF THE INVENTION

It is a principal feature of the present invention to provide a novel adjustable or collapsible butt-stock that is receivable by a receiver extension member of a shoulder fired firearm and incorporates a locking mechanism having a locking member that selectively engages within spaced locking recesses of the receiver extension member to secure the butt-stock mechanism against movement from a selected position.

It is another feature of the present invention to provide a novel collapsible or adjustable butt-stock mechanism having locking and lock release conditions that are achieved by actuation of a trigger-like pull ring lock actuator mechanism to free the butt-stock member for extension of collapsing movement relative to a receiver extension member or to secure the locking mechanism in a locking condition to secure the butt-stock member against movement from any of a plurality of positions relative to the receiver extension member.

It is also a feature of the present invention to provide a novel collapsible or adjustable butt-stock mechanism having a locking selector mechanism that is positionable for locking and lock release conditions and which is positionable to permit selection of a locking position that provides for butt-stock movement to selective positions between positions of minimum extension and maximum extension and a release position permitting selective length adjustment and complete separation of a butt-stock from its tubular support.

Briefly, the various objects and features of the present invention are realized through the provision of a receiver extension member of a shoulder fired firearm, the receiver extension member defining a plurality of spaced locking pin receptacles that are situated along a portion of the length thereof. A collapsible or adjustable butt-stock member defines a receiver extension receptacle within which a rear end portion of the receiver extension member is received for linear movement. The butt-stock member incorporates a substantially vertically moveable locking pin that has a locking position establishing locking engagement within one of the spaced locking pin receptacles and an unlocking or release condition where the locking pin is retracted from the spaced locking pin receptacles. The butt-stock mechanism also incorporates a locking pin actuator that is actuated by a trigger-like pull ring lock release actuator that is manually moved against the bias of a locking pin spring member which urges the locking pin toward its locking condition.

A trigger-like pull ring member is located for lock actuating movement within an opening in the triangular web of the collapsible or adjustable butt-stock member and is connected with the lock actuator member. Manual pulling of the pull ring member achieves linear movement of the locking pin actuator member and causes tapered cam surfaces of the locking pin actuator member to apply a downwardly directed force to a transversely oriented drive pin that is mounted to the locking pin member. This downwardly directed force causes downward movement of the locking pin, thus retracting the upper end of the locking pin from one of the butt-stock positioning receptacles 18 and freeing the butt-stock member for forward or rearward adjustment movement. If the pull ring member is pulled further rearwardly, the upper end of the locking pin will be moved to a position that is clear of the downwardly extending or projecting boss within which the butt-stock positioning receptacles are defined, thus permitting the butt-stock to be moved to its position of maximum extension or completely separated from the receiver extension, depending upon the pre-set locked or unlocked position of a rotatable locking selector.

To ensure that the butt-stock mechanism does not become inadvertently, separated from the buffer tube of the firearm, when adjusting the position of the butt-stock to its position of maximum extension, the rotatable locking selector is located at its locked position. The rotatable locking selector is in the form of a rotatable knob that is located in the end of the reciprocating pull ring operated shaft. The selector rotates a shaft that has an open ended slot in the end opposite the knob. The end of the shaft will contact the roll pin when in the locked position, preventing the trigger-like pull ring assembly from being pulled back so far as to allow the stock to be removed. When the locking knob is rotated 90 degrees to the unlock position, the slot in the shaft will then straddle the roll pin, allowing the pull ring assembly to move farther along its axis. The additional movement of the pull ring assembly moves the vertical locking pin farther down, allowing the stock to be removed from the buffer tube.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.

It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

In the Drawings:

FIG. 1 is a side elevation view of an adjustable or collapsible butt-stock that is constructed in accordance with the principles of the present invention and represents the preferred embodiment of the invention;

FIG. 2 is a side elevation view of the adjustable or collapsible butt-stock of FIG. 1 showing actuation of the adjustment mechanism thereof to permit lengthening, shortening, removal or assembly of the butt-stock mechanism relative to a receiver extension tube that extends rearwardly from the receiver of a firearm

FIG. 3 is a top view of the adjustable or collapsible butt-stock of FIGS. 1 and 2;

FIG. 4 is a rear elevation view of the adjustable or collapsible butt-stock of FIGS. 1-3, with the butt pad thereof removed to expose a cavity or compartment within which tools, parts and cleaning supplies may be stored;

FIG. 5 is a side elevation view of a rear portion of the adjustable or collapsible butt-stock of FIGS. 1-4,

FIG. 6 is a longitudinal sectional view elevation view of the adjustable or collapsible butt-stock of the present invention, taken along line 6-6 of FIG. 7 and showing the locking and lock release mechanism in the locked condition thereof;

FIG. 7 is a front elevation view illustrating the receiver extension receptacle of the adjustable or collapsible butt-stock of this invention and showing the position of a position locking pin of the locking and release mechanism in relation to the receiver extension receptacle;

FIG. 8 is an isometric illustration showing the left side portion of the adjustable or collapsible butt-stock of the present invention;

FIG. 9 is a side elevation view showing a receiver extension member having a plurality of downwardly facing lock pin receiving slots

FIG. 10 is an isometric illustration taken from the right and rear of the adjustable or collapsible butt-stock of the present invention and, with the butt pad removed, showing the rear compartment and shoulder strap opening in detail;

FIG. 11 is a bottom view of the adjustable or collapsible butt-stock, showing further details of the locking pin receptacle and linearly moveable locking pin of the butt-stock mechanism;

FIG. 12 is another isometric illustration taken from the right and rear of the adjustable or collapsible butt-stock of the present invention, showing the receiver extension receptacle, the storage compartment and sling mounting slot and sling connection socket in detail;

FIG. 13 is an exploded isometric illustration showing a butt-stock mechanism representing an alternative and preferred embodiment of the present invention, incorporating a rotatable locking member having an unlocked position permitting complete removal of the butt-stock mechanism from the buffer tube of a firearm and a locking position preventing the butt-stock mechanism from being removed from the buffer tube and further showing internal compartments within the stock body for accessories, such as a gun cleaning kit;

FIG. 14 is a longitudinal section view taken along line 14-14 of FIG. 16;

FIG. 15 is a longitudinal section view taken along line 15-15 of FIG. 15;

FIG. 16 is a rear elevation view of the butt-stock mechanism shown in FIGS. 13-15;

FIG. 17 is a fragmentary section view showing the locking and lock selector mechanism of FIG. 14 in greater detail; and

FIG. 18 is also a fragmentary section view taken horizontally and further showing the locking and lock selector mechanism of FIG. 14 in greater detail.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings and first to FIG. 1, a collapsible and adjustable butt-stock mechanism, representing the preferred embodiment of the present invention, is shown generally at 10 and is adapted for moveable and adjustable mounting to an elongate receiver extension member 12 that projects rearwardly from the receiver of a shoulder fired firearm. In the case of AR-15 type tactical firearms, the receiver extension member is mounted to the lower receiver and is in the form of a buffer tube having an internal action spring and a buffer mechanism to which the rearwardly directed force of the bolt carrier and bolt are applied when a cartridge is fired. Though the present invention is applicable to a wide range of shoulder fired firearms, for purposes of simplicity the invention is described herein particularly as it applies to AR-15 type tactical firearms.

The receiver extension member 12 is typically of generally cylindrical tubular form and is provided with a forward externally threaded end portion 14 that is threaded into an internally threaded receptacle of the lower receiver of the firearm. The upper receiver, to which the barrel of the firearm is mounted, is pivotally mounted to the lower receiver, thus permitting the receiver mechanism of the firearm to be unlocked and opened when access to its internal components is desired. The receiver extension member 12 also defines an external, downwardly extending elongate boss or projection 16 having a multiplicity of spaced downwardly facing butt-stock positioning receptacles 18 situated along the length thereof. The external, downwardly extending elongate boss or projection 16 has a generally rectangular cross-sectional configuration that is defined by generally parallel planar side surfaces 20 and 22 and a bottom surface 24 as shown in FIGS. 1, 4, 9, 11 and 12. FIG. 9 illustrates the geometry of the receiver extension member 12 in greater detail and is discussed in further detail below.

The butt-stock mechanism 10 defines a butt-stock member 25 having a housing section 26, within which is defined a receptacle chamber 28 of generally cylindrical internal configuration, with the receptacle chamber 28 opening downwardly to an internal elongate slot 30 that is defined by internal generally parallel slot side surfaces 32 and 34 and an internal bottom surface 36 as evidenced by FIG. 4. The receptacle chamber 28 of the housing section is basically in the form of a generally cylindrical through passage that receives the generally cylindrical receiver extension member 12 in sufficiently close fitting relation therein that the butt-stock mechanism is prevented from any lateral movement within the through passage and thus is not susceptible to rattling or other undesirable characteristics of movement relative to the receiver extension member.

Beyond the rear end of the receiver extension member 12 the through passage that defines the receptacle chamber 28 defines a storage chamber or compartment 38 within which tools, cleaning equipment or parts may be stored for use as needed. A butt pad member 40 is movably or removably mounted to the rear end surface 42 of the butt-stock housing section 26. As shown in FIG. 5, the butt pad member 40 is shown to have been pivoted downwardly about a mounting screw that is threaded into a screw hole 44, shown in FIG. 4, to expose the storage compartment and permit access to its contents. The butt-stock housing section 26 also defines tapered elongate cheek weld surfaces 46 and 48 that are typically engaged by the cheek of the user to provide for comfort and to properly position the head of the shooter during shooting activity. If desired, the cheek riser sections 50 and 52 of the butt-stock member 25, that defines the cheek weld surfaces 46 and 48, may also define internal compartments for cleaning rods and other desirable tools, equipment and supplies.

The butt-stock member 25 also defines a generally triangular body web 54 defining an elongate slot 56 within which a firearm sling member can be received and defining various thickened web portions that provide other features. For example, within the thickened web portion 58 defines a sling socket 60 within which a sling swivel of a quick connect firearm sling can be positioned and locked. The thickened web portion 58 also provides structure within which a rear slot or cavity 62 can be defined so that one or more tools may be stored within the slot or cavity for access when the butt pad 40 is moved to the open or out of the way position that is shown in FIG. 5. A thickened web region 62 represents a butt-stock section within which the screw hole 44 can be extended to provide for secure threaded reception of a butt pad retainer screw. It should be borne in mind that the thickened regions of the generally triangular web 54 are provided in the interest of minimizing the weight of the butt-stock mechanism, since the butt-stock will typically be molded or otherwise formed of a metal such as an aluminum alloy. If desired, the butt-stock may be provided in generally conventional form and the internal openings, passages and other structures may be formed by machining operations.

The generally triangular body web 54 also defines a pair of elongate thickened regions 64 and 66 that are disposed in intersecting relation with one another. Additionally, the elongate thickened region 64 intersects an edge flange 68 of the generally triangular web 54 and also intersects the housing section 26 in the region of the elongate slot 30. As is evident in the longitudinal sectional view of FIG. 6, a substantially vertical passage 70 extends through the thickened region 64 and defines a passage having a lower opening 72 at the edge flange 68 and an upper opening at the elongate internal slot 30. A butt-stock locking pin 74 is movably disposed within the passage 70 and has an upper end 76 that is moveable from a retracted position within the passage 70 to a projected position where the upper end 76 of the locking pin 74 is located within the elongate internal slot 30, as shown in FIG. 7.

The lower end portion of the locking pin 74 is bifurcated and defines an elongate slot 78 within which is located a guide pin 80 having end portions of the guide pin located within opposed pin openings 82 and 84. This feature permits linear movement of the locking pin 74 within limits that are defined by the length of the elongate slot 78. The locking pin 74 is urged toward its locking condition by a locking pin spring member 86 that is located within a spring chamber 88. An upper end portion of the locking pin spring member 86 engages a spring washer member 90 that is located within the passage 70 while a lower end portion of the locking pin spring member is restrained by contact with the transversely oriented guide pin 80.

The generally horizontally oriented elongate thickened region 64 defines an internal actuator passage 94 within which a locking pin actuator member 96 is linearly moveable within limits that are defined by the length of an elongate slot 98, within which a transversely oriented stop pin 100 is located. The transversely oriented stop pin 100 extends through aligned stop pin mounting holes 102, which are visible in FIGS. 8 and 11. The stop pin 100 may be press-fitted within the stop pin mounting holes or may be secured in place by threaded attachment or by any other suitable means. The locking pin actuator member 96 defines a recess 104 intermediate the length thereof, the recess being defined in part by tapered cam surfaces 106. An actuator pin 108 extends through the locking pin 74, with end portions of the actuator pin having engagement with the tapered cam surfaces 106. The locking pin actuator member 96 is linearly moveable within the internal actuator passage 94 and is provided with a generally vertically oriented slot 110 which permits actuator movement within limits that are defined by the length of the slot 110.

Within the generally triangular body web 54 an actuator pull ring opening 112 is defined and a trigger-like pull ring member 114 is moveable within the pull ring opening. The pull ring member 114 is fixed to the rear end portion of the lock pin actuator member 96 so that a manually applied rearward force to the pull ring member achieves linear movement of the lock pin actuator member. Linear rearward movement of the lock pin actuator member causes cam energized force transition resulting in a downward force application to the locking pin, moving the locking pin downwardly against the upward force of its spring. This downward movement retracts the upper end portion of the locking pin from one of the spaced butt-stock positioning receptacles and frees the butt-stock mechanism for adjustment movement relative to the receiver extension member 12.

With reference to FIG. 9, the forward and rearward downwardly projecting portions 113 and 115 of the external downwardly extending boss or projection 16, extend downwardly to a greater extent as compared with an intermediate portion of the boss or projection 16, thus defining forward and rearward movement stop shoulders 116 and 118. Between the stop shoulders 116 and 118, the downwardly extending boss or projection 16 extends downwardly to a lesser extent and multiple spaced portions of it are cut away, thus defining the plurality of spaced locking recesses 18. With the butt-stock at one of its locked positions relative to the receiver extension member 12, the upper end portion of the locking pin 74 is maintained within one of the spaced locking receptacles 18, thus securing the butt-stock mechanism 129 against movement from the locked position.

When the pull ring member 114 is pulled rearwardly to an intermediate position within the pull ring opening 112 that is defined in the generally triangular web of the butt-stock, the actuator member 74, being connected with the pull ring member, will be moved rearwardly to an intermediate position, thus driving the locking pin downwardly sufficiently to extract the upwardly facing tip of the locking pin from the locking receptacle. At this intermediate and unlocked position of the locking pin, the butt-stock member will be free for forward or rearward positioning movement. However, at the intermediate position of the locking pin 74, the locking pin will contact either the forward stop shoulder 116 or the rear stop shoulder 118, thus stopping adjustment movement of the butt-stock relative to the receiver extension member 12. This feature prevents the butt-stock from being pulled rearwardly to the extent that it is separated from the receiver extension member. When the pull ring member 114 has been moved rearwardly to its maximum extent, the locking pin 74 will be fully retracted and its tip portion will clear the stop shoulders 116 and 118. This feature permits the butt-stock to be collapsed to its maximum extent for storage or special handling and permits the butt-stock to be moved rearwardly until it becomes separated from the receiver extension member.

Referring now to FIGS. 13-18, which show an alternative and preferred embodiment and best mode of the present invention, a butt-stock mechanism is shown generally at 120 which incorporates the features that are discussed above concerning FIGS. 1-12 and additionally incorporates a rotatable locking selector member which is manually set to a locking position to prevent complete separation of the butt-stock mechanism from the buffer tube of the firearm when the butt-stock is moved to its maximum extended position. In the event the butt-stock is to be intentionally removed from the buffer tube, the locking selector is manually position at an unlocked position so that the firearm user can move the pull ring to its maximum rearward position, thus moving the locking pin to a position clearing the rearmost locking shoulder of the downwardly projecting boss 16 of the receiver extension member, which is also referred to as a buffer tube.

As shown in FIGS. 13 and 14 a butt-stock mechanism is shown generally at 120 and has a butt-stock body member 122 that defines an inner buffer tube chamber 124 of a configuration and dimension to receive the buffer tube or receiver extension member 12 of a tactical firearm, which is shown in FIGS. 1, 3, 6 and 8-10 of the drawings. The lower central portion of the inner buffer tube chamber 124 defines an open ended elongate slot 126 that is of a configuration and dimension to receive the downwardly projecting boss or projection 16 of the receiver extension or buffer tube 12.

A locking pin housing 128 is integral with and extends downward from the butt-stock body member 122 and defines an internal passage 123 within which a locking pin 130 is received for linear movement. The upper end of the locking pin is shown in FIG. 14 to be located within the elongate slot 126 for selective engagement within a locking recess 18 of the buffer tube to secure the butt-stock body at a desired position along the length of the buffer tube. The locking pin member 130 is urged upwardly by a compression spring member 132 which is secured within a spring chamber 134 of a lower enlargement of the locking pin by means of a roll pin 136. The ends of the roll pin 136 are received by aligned holes in the body of the butt-stock so that the position of the roll pin is fixed with respect to the body 122. The locking pin 130 defines elongate recesses 137 at each of its sides, which receive the roll pin and permit linear movement of the locking pin within the passage 123. A dowel pin 138 is received within a transverse passage or hole of the locking pin 130 and is moved within the butt-stock body 122 along with the locking pin 130. The ends of the dowel pin are received by bushing members 139 that are located within elongate openings 141 of the lock pin housing 128. The bushing members serve to guide downward movement of the dowel pin 138 and the locking pin 130 during cam actuated unlocking movement of the locking pin.

A lock actuator passage 140 is defined within the butt-stock body structure below the buffer tube passage 124 and the elongate slot 126 that is a part of the buffer tube passage. A locking pin actuator 142 is located for linear movement within the buffer tube passage 124 and defines tapered surfaces 144 that are disposed for locking pin actuating engagement with the dowel pin 138. The locking pin actuator 142 is secured to a trigger-like pull ring member 146 by a pair of retainer screws 148, and is similar or identical to the pull ring member 114 that is discussed above in connection with FIGS. 1-12. Manual application of a pulling force on the pull ring member 146 causes movement of the locking pin actuator 142 toward the left, as shown in FIGS. 14-17, causing the tapered cam surfaces 144 to apply a downwardly directed force to the locking pin 130, moving the locking pin downward, against the force of its compression spring 134. This downward locking pin movement causes the upwardly facing tip of the locking pin to be extracted from a positioning recess 18 of the buffer tube boss structure 16. Another roll pin 150 is extended through pin openings of the locking pin actuator 142 and serves to retain a compression spring 152 within a spring chamber 154 of the locking pin actuator. Portions of the roll pin 150 are located with elongate guide slots 151 that are defined by the locking pin actuator 142. An end of the compression spring 152 is disposed in force applying contact with a spring retainer shoulder 156 of a flange member 158 of a lock positioning shaft 160. The lock positioning shaft, as shown in FIG. 18, defines a bifurcated end portion 161 forming a yoke recess 162. The yoke recess is of a configuration and dimension to receive the roll pin when the lock positioning shaft 160 is rotated 90° to an unlocked position from the position that is shown in FIG. 18.

The lock positioning shaft 160 is at its locked position as shown in FIG. 18. In this position the yoke recess 162 is misaligned with respect to the roll pin 150, thus limiting linear movement of the shaft 160 and consequently limiting downward movement of the locking pin 130, so that the tip of the locking pin cannot move downwardly to a position causing the tip of the locking pin to clear the stop shoulder 118 of the boss structure 16 of the buffer tube 12. In the locking position of the lock positioning shaft 160, the butt-stock mechanism cannot become separated from the buffer tube of the firearm.

A lock positioning knob 164 is fixed to the outer end portion of the lock positioning shaft 160 by means of a roll pin 166 to provide for 90° manual rotation of the lock positioning shaft between its locked position and its unlocked position. A detent member 168 is urged by a compression spring member 170 into detent recesses 172 that are rotationally spaced by 90° for the locked and unlocked position of the lock positioning knob 164. As a user applies manual rotational force to the lock positioning knob, the detent member 168 will be forced from a detent recess, against the bias of the compression spring, thereby permitting rotary movement of the lock positioning knob and thus the lock positioning shaft 160. When the detent reaches the selected detent recess it will be snapped into the recess by the force of the compression spring 170. A knob positioning control pin 174 is provided to limit rotational movement of the lock positioning knob to 90° regardless of its direction of rotation.

Referring again to the exploded isometric illustration of FIG. 17, body structure 122 of the butt-stock mechanism defines internal compartments 176, 178 and 180 within which accessories such as cleaning rods, gun powder solvent and lubricant are stored. To prevent the accessories from rattling and making undesired noise when the position of the butt-stock is changed, accessory kits, such as shown at 182 and 184, are received in close fitting relation within the accessory compartments 176 and 178.

A butt-plate member 186 is pivotally mounted to the rear portion of the body 122 of the butt-stock and is normally secured at a closed position, as shown in FIGS. 14 and 15. The rear portion of the body 122 defines a spring detent receptacle 188 within which is located a spring member 190 and a detent plunger member 192. A detent retainer sleeve 194 is secured within the spring detent receptacle 188 by the butt-plate member 186. The butt-plate detent mechanism permits the butt-plate to be retained securely in place and to be readily pivotally moveable to a position exposing the internal assessory compartments 176, 178 and 180 so that the gun cleaning accessories can be removed from the respective compartments and used.

In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein.

As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein. 

I claim:
 1. An adjustable butt-stock mechanism for a shoulder fired firearm, comprising: a receiver extension member being mounted to a firearm receiver and having an elongate boss member defining a plurality of spaced position adjustment recesses along the length thereof; a butt-stock body defining a receiver extension passage within which said receiver extension member is movably received and selectively positioned, said butt-stock body defining a lock passage and having a web portion defining a pull member opening; a locking pin being movably located within said lock passage and having a portion thereof being located within said receiver extension passage and having selective locking engagement within a selected one of said spaced position adjustment recesses; a locking pin actuator having force transmitting engagement with said locking pin and upon being manually moved causing unlocking movement of said locking pin from said spaced position adjustment recesses; and a trigger-like pull member being located within said pull member opening and having connection with said locking pin actuator and being disposed for application of manual pulling force by a user to cause unlocking movement of said locking pin actuator and said locking pin.
 2. The adjustable butt-stock mechanism of claim 1, comprising: an urging member continuously urging said locking pin toward said locking position thereof; and said locking pin actuator overcoming said urging member and moving said locking pin toward an unlocking position with said locking pin extracted from said spaced position adjustment recesses.
 3. The adjustable butt-stock mechanism of claim 1, comprising: said locking pin having a cam engagement surface; and said locking pin actuator having a tapered cam surface in engagement with said cam engagement surface and upon being moved linearly by a manually energized pulling, force causing unlocking movement of said locking pin.
 4. The adjustable butt-stock mechanism of claim 1, comprising: a manually positionable locking selector being mounted to said locking pin actuator and having a first selector position limiting unlocking movement of said locking pin by said locking pin actuator and a second selector position permitting complete unlocking movement of said locking pin by said locking pin actuator for complete separation of said adjustable butt-stock from said receiver extension member.
 5. The adjustable butt-stock mechanism of claim 4, comprising: a locking position element being mounted to said manually positionable locking selector and establishing a locking reference; and said manually positionable locking selector having a selector shaft being moveable to a first position having movement limiting contact with said locking position element and limiting linear unlocking movement of said locking pin actuator and being moveable to a second position permitting complete unlocking movement of said locking pin.
 6. The adjustable butt-stock mechanism of claim 5, comprising: said locking position element being a pin member mounted to said locking pin actuator; said selector shaft having a bifurcated end portion defining a recess receiving said locking position element when said selector shaft is situated at said first position; and a manually operable selector knob being mounted to said selector shaft and having first and second rotational positions having 90° rotational spacing.
 7. The adjustable butt-stock mechanism of claim 1, comprising: a manually positionable locking selector being mounted to said locking pin actuator and having a first selector position limiting unlocking movement of said locking pin by said locking pin actuator and a second selector position permitting complete unlocking movement of said locking pin by said locking pin actuator for complete separation of said adjustable butt-stock from said receiver extension member; a locking position element being mounted to said manually positionable locking selector and establishing a locking reference; and said manually positionable locking selector having a selector shaft being moveable to a first position having movement limiting contact with said locking position element and limiting linear unlocking movement of said locking pin actuator and being moveable to a second position permitting complete unlocking movement of said locking pin.
 8. The adjustable butt-stock mechanism of claim 1, comprising: a lock actuator passage being defined within said butt-stock body; said locking pin actuator being linearly moveable within said lock actuator passage responsive to application of a pulling force thereto; a lock selector shaft being rotationally moveable within said locking pin actuator; and a lock selector knob being mounted to said lock selector shaft and being manually rotatable to a first position limiting linear unlocking movement of said locking pin actuator and being moveable to a second position permitting complete unlocking movement of said locking pin.
 9. The adjustable butt-stock mechanism of claim 8, comprising: a spring member urging said lock selector shaft against an internal stop shoulder of said locking pin actuator and yielding to permit rotational lock positioning movement of said lock selector shaft.
 10. The adjustable butt-stock mechanism of claim 9, comprising: said locking in actuator defining a pair of detent recesses having 90° rotational spacing; a spring urged detent member being supported by said lock selector knob and being disposed for selective engagement within said detent recesses and establishing said first and second locking positions of said locking pin.
 11. An adjustable butt-stock mechanism for a shoulder fired firearm, comprising: a receiver extension member being mounted to a firearm receiver and having an elongate boss member defining a plurality of spaced position adjustment recesses along the length thereof; a butt-stock body defining a receiver extension passage within which said receiver extension member is movably received and selectively positioned, said butt-stock body defining a lock passage and having a web portion defining a pull member opening; a locking pin being movably located within said lock passage and having a portion thereof being located within said receiver extension passage and having selective kicking engagement within a selected one of said spaced position adjustment recesses; a locking pin actuator having force transmitting engagement with said locking pin and upon being manually moved causing unlocking movement of said locking pin from said spaced position adjustment recesses; a trigger-like pull member being located within said pull member opening and having connection with said locking pin actuator and being disposed for application of manual pulling force by a user to cause unlocking movement of said locking pin actuator and said locking pin; a locking position element being mounted to said manually positionable locking selector and establishing a locking reference; and said manually positionable locking selector having a selector shaft being moveable to a first position having movement limiting contact with said locking position element and limiting linear unlocking movement of said locking pin actuator and being moveable to a second position permitting complete unlocking movement of said locking pin.
 12. The adjustable butt-stock mechanism of claim 11, comprising: an urging member continuously urging said locking pin toward said locking position thereof; and said locking pin actuator overcoming said urging member and moving said locking pin toward an unlocking position with said locking pin extracted from said spaced position adjustment recesses.
 13. The adjustable butt-stock mechanism of claim 11, comprising: said locking pin having a cam engagement surface; and said locking pin actuator having a tapered cam surface in engagement with said cam engagement surface and upon being moved linearly by a manually energized pulling force causing unlocking movement of said locking pin.
 14. The adjustable butt-stock mechanism of claim 11, comprising: a manually positionable locking selector being mounted to said locking pin actuator and having a first selector position limiting unlocking movement of said locking pin by said locking pin actuator and a second selector position permitting complete unlocking movement of said locking pin by said locking pin actuator for complete separation of said adjustable butt-stock from said receiver extension member.
 15. The adjustable butt-stock mechanism of claim 14, comprising: a locking position element being mounted to said manually positionable locking selector and establishing a locking reference; and said manually positionable locking selector having a selector shaft being moveable to a first position having movement limiting contact with said locking position element and limiting linear unlocking movement of said locking pin actuator and being moveable to a second position permitting complete unlocking movement of said locking pin.
 16. The adjustable butt-stock mechanism of claim 15, comprising: said locking position element being a pin member mounted to said locking pin actuator; said selector shaft having a bifurcated end portion defining a recess receiving said locking position element when said selector shaft is situated at said first position; and a manually operable selector knob being mounted to said selector shaft and having first and second rotational positions having 90° rotational spacing. 